T-Max 400 has boomerang curve

Originally Posted by Michael R 1974

Just don't get too carried away with it, Stone. Often people plot curves and think they know what they are going to get but drawing meaningful conclusions from the data can actually be tricky. There are different ways of testing, and many variables, including differences between testing conditions and shooting conditions.

You might want to get yourself a copy of Ansel Adams's The Negative. There is an easy to understand primer on densitometry and characteristic curves in the book.

Incidentally, to anyone who owns a copy of Haist, the end of the first book has a pretty good chapter on sensitometry/densitometry, curves etc. Just mentioning it because while Haist is a common reference for photochemistry, there's other excellent stuff in there too.